Manufacturing transistors which perform properly requires accurate and stable photolithography and process techniques. Design rules for transistors have become more strict due to ever larger scale integration of semiconductor devices. It is necessary to use an ArF light source, instead of a KrF light source, for the manufacture of transistors with a line width of 100 nm or less. The resolution in a photolithography process is inversely proportional to the wavelength of an exposure light source. The wavelength of a KrF excimer laser is 248 nm, whereas the wavelength of an ArF excimer laser is 193 nm. However, the ArF light source requires expensive equipment and a specific photoresist material. This may increase the manufacturing costs of the semiconductor device.